A variety of techniques and apparatus have been used to satisfy the requirements of automated currency handling systems. At the lower end of sophistication in this area of technology are systems capable of handling only a specific type of currency, such as a specific banknote (Euro or dollar) denomination, while rejecting all other currency types. At the upper end are complex systems which are capable of identifying and discriminating among and automatically counting multiple currency denominations.
Recent currency discriminating systems rely on comparisons between a scanned pattern obtained from a subject bill and sets of stored master patterns for the various denominations among which the system is designed to discriminate. There are a wide variety of bill sizes among different countries and even within the same currency system. Likewise, many other characteristics may vary between bills from different countries and of different denominations, such as, for example, the placement of a magnetic thread within the currency bills. The location of a magnetic thread within the currency bill and the information contained thereon can vary for different countries and different denominations as well as for different series of denominations.
Many types of currency bills possess magnetic attributes exhibiting magnetic properties which can be used to uniquely identify and/or authentic the currency bills. Examples of magnetic attributes include security threads exhibiting magnetic properties and ink exhibiting magnetic properties with which portions of some bills are printed. Many of these magnetic attributes have a very small dimension(s). For example, many magnetic threads have a width on the scale of millimeters. These security threads may be formed from an intermittent-magnetic pattern, such that the segments of magnetic and nonmagnetic material may characterize a code. These segments generally have a fixed or variable length and may form a code, which may be repeated along the magnetic thread.
Typically, the presence of—and the information in—the magnetic code is determined using difficult and often complex algorithms to reconstruct code from the data obtained from numerous data channels. Standard magnetic-thread authentication and decoding techniques require time shifting the magnetic-code data to account for the velocity differences between the bills as they pass by the scan head. Such a technique is time consuming and requires additional electronic circuitry to perform the time-shift calculations.